Feed table for grinding mbuls



OC. 11, 1938. C;- F SCHUTTE 2,133,211

FEED TABLE FOR GRINDING MILLS Filed May 1, 1957 Patented ct. 171, 1938 UNITED STATES 2,133,211 Y FEED TABLE Fon GRJNDINGMILLS Charles F. Schutte, Bulalo, N. Y. Application .Maya 1937, seirNo. 140,263'

2 Claims.

This invention relates to grinding mills and more particularly toa feed table adapted to be associated with a grinding mill and over which the material tobe ground passes prior to its introduction into the mill.v

An important object of my invention is to provide a feed table adapted to be used in conjunction with mills of the type having a closed casing surrounding the grinding mechanism and connected to an exhaust fan for pneumatically removing the ground product therefrom, said feed table incorporating means for separating heavier foreign bodies, such as tramp metal, stones and glass, from the lighter material entering the mill. An advantageous feature of my feed table is the provision of an initial feed chute and a shelf so constructed and arranged relative to the feed chute, that the kinetic energy of the heavier bodies accompanying the material discharging from the feed chute, as well as the draft created by the fan, results in an effective separation of detritus from the material.

Another object of my invention is to provide a feed table of the above character in which the shelf is disposed `beyond and spaced from the discharge end of the feed chute and inclined so as to form a pocket to receive the material passing into the mill, the arrangement being such that the heavier foreign bodies collect in the pocket while the lighter material lodging upon the shelf reverses its direction of flow and spills over a lip into a passage'extending beneath the shelf. and communicating with the interior of the mill.

The invention has as a further object to provide a feed table of the above character including an upright plate at an end of the shelf remote from its lip and disposed in the path of the material discharging from the feed chute, this plate being removable to permit the material t0 flow directly into the mill without separation.

Y ther objects and advantages will be apparent from the following detailed description of a preferred embodiment of. the invention, reference being had to the accompanying drawing in which:

Figure 1 is a view in side elevation of a hammer mill having a feed table associated therewith for separating heavy foreign bodies from the 50 material passing into the mill;

Figure 2 is a perspective view of the feed table; and

Figure 3 is a vertical cross-section through the feed table illustrating its mode of operation.

In Figure 1 is illustrated a hammer mill having a. casing l enclosing the grinding mechanism, not shown, but which may be of any of the usual types. `As is customary in mills of this general character, the casing isair tight except for an opening 2 adjacent vits top through which materialis introduced into the mill and is provided with an exhaust fan 3 communicating at onel end of the mill with the interior of the casing for pneumatically removing the finely ground material from the mill and delivering it to a collector or separator, as is well understood in the art.

In the grinding of certain classes of material, such as grain, it is not unusual for suchcmaterial in the bulk form in which it is received at the plant for grinding to include foreign bodies, such as tramp metal, stones'and glass, which should not be permitted to enter the mill, either because of the possible damage they may cause to the grinding mechanism or because of the undesirability of. their presence in the ground productdelivered from the mill.

For separating such foreign bodies from the lighter material feeding into the mill, there is provided a feed table lldisposed at an inclination and having its lower end extending into the opening 2 adjacent the topof the mill casing.

The feed table is made of .heavy sheet metal and, as best shown in Fig. 2, vcomprises a pair of side walls 5 extending throughout its length and a bottom portion 6 .extending between the side Y walls 5 and constituting therewith a feed chute A for receiving material for introduction into the mill. The bottom 6 does not extend the full length of the feed table but beginning at the elevated material-receiving end of the table it slopes downwardly for the-major length ofthe feed ltable and terminatesviin a straight edge 6a. Located at an'elevation below and in a plane approximately'parallel tothe bottom 6 is a flat shelf `v l, this shelfPbeing Vdisposed beyond the end of the feed -chute'.v The lshelffis provided with a narrow upright lip 8 upon one end which is located directly below the straight edge 6a of. chute A but with respect to which it provides a short space or gap B.

4The end of the shelf which is located remote from the end of the chute terminates in an edge 9 located inwardly of thelower or discharge end of the feed table. For closing the end of the shelf adjacent the edge 9 is an upright plate l0 slidable Within guide slots Il provided along the vertical edges of ears I2 upstanding from the upper edges of the side Walls 5 of. the feed table. The plate may thus be manually raised and lilV lowered onto and off of the shelf lI. This plate when in lowered operative position constitutes a vertical wall located in the path of the material flowing from the discharge end of the chute and forming with the shelf a closed pocket for the reception of material discharged from the chute, as indicated in Fig. 3.

Below the shelf is a second bottom I3 extending between the sides of the feed table and forming therewith a closed passage C extending from the space or gap B between the adjacent ends of the feed chute and the shelf to that end of the feed table communicating with the interior of the mill casing. As will be apparent from Fig. 2, the side walls 5 of the feed table are dropped or widened to provide space for the passage C below the shelf and the bottom I3 is joined to the bottom 6 of the feed chute a spaced distance inwardly of its edge 6a by an inclined portion I3a closing the end of the passage. The feed table is pivotally supported in position upon the casing of the mill by means of bolt I4 passing through suitably provided openings in the mill casing and through a sleeve I5 rolled from the bottom I3 at its end which projects within the feed inlet 2 of the mill. A strut I6 extending between the mill casing and the outer or elevated end of the feed table serves to provide support for the latter and to allow adjustability of the inclination of the feed table.

A cleanout opening I'I formed in a side Wall 5 of the feed table adjacent the end of the inclined shelf which is closed by the plate II) affords means for removing debris accumulating upon the shelf. A pivoted cap I8 is suitably provided to maintain this cleanout opening closed.

As indicated in the cross-sectional view of Fig. 3, material passing oif the discharge end of the chute A strikes the upright plate I0 and lodges on the shelf 'I where it banks up against the plate in the sloping manner shown. Heavy bodies such as pieces of metal, stones or bits of glass, accompanying the material will under the force of gravity embed themselves deeply in the layer of material reposing on the shelf, While the lighter material will slide over the lip 8 at the open end of the shelf and into the passage C under the combined influence of gravity and the current of air (shown by dotted lines in Fig. 3) being sucked into the mill by the fan F through the restricted space B intermediate the discharge end of the chute and the adjacent end of the shelf. As the lighter material is continuously removed from the shelf the heavy bodies will remain behind and accumulate in the pocket formed by the inclined shelf and the upright slide I0 and these foreign bodies may be removed from time to time through the cleanout opening I1.

When no separation is to be made all that is necessary is to raise or remove the slide plate I0 so as to allow the material to flow directly off the edge 9 of the shelf into the mill, in which case the shelf 1 will constitute in effect a continuation of the feed chute A, and the passage C will act as a by-pass only for such material as may incidentally drop down through the gap B.

Manifestly various changes in construction and design may be made in the feed table described above, which represents one embodiment of the invention, Without departing from the spirit of my invention.

I claim:

1. A feed table for use in conjunction with grinding mills of the type having an enclosing casing, said feed table comprising a pair of side walls, an inclined elongated bottom extending between the side walls for a portion of their length and forming therewith an open-topped chute for the gravitational feed of material therealong, a shelf extending between the side walls, said shelf being arranged at an inclination corresponding to the bottom and located at an elevation below and projecting forwardly beyond the lower end of the chute so as to provide a restricted opening between the adjacent ends of the chute and the shelf, a Wall normally clos-A ing the lower end of the shelf for intercepting material discharged from the lower end of the chute but said wall being so arranged to be moved to non-intercepting position, a second bottom located a spaced distance below the shelf and extending between the side walls to form a passage below the shelf, said second bottom being arranged at an inclination corresponding to the first-mentioned bottom and being open at its lower end so as to discharge intothe casing, and an end wall closing the upper end of the passage but providing communication between the passage and the restricted opening between the adjacent ends of the chute and shelf, whereby heavier bodies accompany the material passing down the chute are forcibly discharged against and embedded within the sloping face of the material filling the shelf.

2. A separating feed table for grinding mills and the like comprising an inclined chute for cooperation with the feed entrance of the mill, said chute having upstanding side walls with an upper inclined bottom Wall at the outer portion of the chute followed by a lower bottom wall similarly inclined and extending in a plane below the plane of the first bottom wall and to the inner end of the chute, a similarly inclined shelf extending in a plane between the planes of the two bottom walls of the chute, said shelf having one end adjacent to but spaced from the first bottom wall and having an upright wall extending upwardly from the other end thereof and forming therewith a separating pocket for receiving heavier objects as they pass down the chute, said upright wall being removably mounted whereby to permit direct passage over the shelf to the feed entrance upon removal of the upright wall.

CHARLESy F. SCHUTTE. 

